Piston ring grinder



Dec. 15, 1936. c. i.

Original Filed Nov. 23, 1933 L TT 2,063,939

PISTON RING GRINDER 2 Sheets-Sheet l Ill 1936- c. l. LOTT PISTON RING GRINDER Original Filed Nov. 25, 1933 2 Sheets-Sheet 2 6MUJAZ;

Patented Dec. 15, 1936 UNITED STATES PATENT OFFICE Application November 23, 1933, Serial No. 699,443 Renewed February 15, 1938 11 Claims.

This invention relates to apparatus for grinding piston rings.

An object of the invention is to provide mechanism by which piston rings can be ground exactly to dimensionin quantity by treatment of a plurality of the piston rings in one operation.

A further object of this invention is to provide mechanism for holding piston rings during the grinding operation exactly in the shape they will assume in use in acylinder.

A further object of this invention is to provide a cylindrical magnetic drum or arm for holding the piston rings of exactly the inside dimension of the piston rings when in use.

Still another object of this invention is to provide a work holding arbor having a plurality of arms or drums for holding piston rings, one armof which may be loaded with the rings while those on another arm are being ground.

A still further object of this invention is to provide an arbor having work holding arms or drums which are rotatable and upon which piston'rings may be held magnetically in the proper shape whereby the piston rings may be rotated during the grinding operation and the entire outer surfaces of the rings are exposed for the grinding operation.

In the accompanying drawings an embodiment of the invention is illustrated.

In Fig. l a front elevation of the apparatus is shown.

Fig. 2 is a plan view of the apparatus with the wheel housings removed for the sake of clarity.

Fig. 3 is a horizontal view partly in section of the center and one arm of the work holding arbor.

Fig. 4 is a transverse sectional view of an arm of the arbor loaded with piston rings to be ground.

Fig. 5 is a vertical sectional view through the center of the arbor showing certain details thereof.

Fig. 6 is a diagrammatic showing of a modified form of arbor arm or drum suitable for grinding the end faces of piston rings.

In the drawings, numeral l refers to the frame or base of the machine. Upon this base a grinding wheel 2 is rotatably mounted in a frame 3 which is adjustable on the machine base in the direction of the axis of the grind wheel by means of tongue and slot connection 4 and hand-wheel 5. The grind wheel may be provided with a guard housing 6 of conventional character and any suitable wheel dresser I.

On the machine base I opposite the grind wheel 2 a work driving grind wheel 8 is rotatably mounted in a frame 9. The frame 9 is adjustable on the base I to and fromthe direction of the grind wheel 2 by means of a tongue and slot connection [0 and hand-wheel II. The grind wheels 2 and 8 are driven from any suitable source 01 power through belts l2 and I3.

The machine base is provided with a forwardly extending portion I4 which has an arbor l5 slidably mounted thereon by means of slide it and tongue and slot connection ll. A hollow spindle 20 extends upwardly from the slide it. This spindie is non-rotatable and has an insulated portion H in which an electrical contact 22 is seated. Upon this spindle an arbor cap 23 is rotatably mounted. The arbor cap has a pair of horizontal oppositely disposed arms or drums 24 and 25.

The arms24 and 25 are identical so that only .one of them need be described. The arm 24 comprises a hollow spindle 28, Fig. 3, extending horizontally from arbor cap 23. Upon this spindle 26 a core extension 21 01. magnetic material is rotatably mounted. .This core is provided with a transverse opening 28 and grooves '29 connected thereto for accommodating an electro-magnetic winding 30. The core.2l may be reduced slightly beyond the end of spindle 26 and this reduced portion is provided with a sleeve 3| preferably of nonmagnetic material. The sleeve is retained on the core by suitable means, such as cap piece 32, secured in position by screws 33. The sleeve 3| should have an outside diameter of exactly the inside diameter of the piston rings when in use in a cylinder. Thus when the rings 34 are drawn tightly about the sleeve and ground in this shape, the rings will be exactly circular and exactly fit the cylinders in which they are later used.

It is considered desirable that the electromagnets of the arms shall be energized only when the arms are substantially in position to be fed through the grinding mechanism. To this end, the spindle cap is provided with a pair of oppositely disposed elongated contacts 35, one for each arm. These contacts are'recessed in insulating material 36 in the arbor cap. The electric feed-in wire 31 passes into the arbor cap and hollow spindle 20 by means of an opening 38 in the top of the cap. The wire passes through an opening in the insulating material of the hollow arbor spindle and is connected to contact 22 thereof. When the arbor'arm 24 is moved to substantially the position for feeding to the grind wheel mechanism, the contact 35 engages with-the contact 22 and the current flows to wire 39 in the hollow arbor arm spindle 26. This wire connects to contact ring 40 which extends around the outside of the arbor arm, spindle, being mounted in insulating ring ll seated in a groove. in the arm spindle. The core 21 is provided with a recess 42 adjacent the contact ring 40, and an insulated spring contact device 43 mounted on the core is disposed in this recess. This contact device is connected with electro-magnetic winding 30 and the opposite end of the winding may be grounded on the core at 44. Upon rotation of the arm 24, the spring contact 48 slides around the contact ring II and maintains the current in the winding 30 continually.

In operation the slide I8 is pulled away from the grinder wheel mechanism and one arm or drum 24 or 25 thereof is loaded with piston rings to be ground. Preferably. the gaps in the rings are placed at the top, and the position of the arm being loaded should be adjusted so that the longitudinal stretches of the winding are at top and bottom. The loaded arm is then turned toward the grinder wheels and the contacts 22 and 35 'come into engagement whereby the electro-magnetic winding 30 is energized and the piston rings are drawn tightly against the sleeve II. The free ends of the rings are drawn together and the gap is closed to some extent, the shape of the ring being similar to that which it will assume in operation in a cylinder of an engine.

The slide it carrying the arbor is then moved manually or by any suitable feed mechanism in the direction of the grinder wheels and the rings coming into contact with said wheels are ground to the desired size and finish. The grinder wheel 2 is considerably larger than grinder wheel 8 and has a considerably greater peripheral speed than wheel I. The wheel 8 takes a stronger frictional grip upon the rings and thus causes the rings and the arm on which they are mounted to rotate upon the arm spindle 26. When all of the rings have beed fed between the grinder wheels and ground to the desired finish, the slide I6 is pulled backwardly and the arm with the ground rings is moved free of the grind wheels. During the grinding operation of the rings on one arm, the opposite arm may be loaded with rings, and after the first grinding operation the arbor may be turned about its spindle whereupon the rings to be ground will be magnetically clamped or. the arm on which they are mounted and the finished rings will be released and may be unloaded. This operation may then be repeated.

It will be apparent that by the operation above described a great many piston rings may be ground to finished size in a short period of time and that the finished shape will be exactly that which the ring will assume when in use in a cylinder.

In Fig. 6 a modified form of the invention is disclosed. In this case the arms or drums 48 of the arbor are wound in the opposite direction to the first-described embodiment as indicated at 49, whereby the magnetic force is exerted axially.

On the ends ofthe arbor arms three or more pins 50 are provided. These pins are so spaced that a piston ring 5| may be placed thereon by slightly expanding the ring. When a ring has been placed in position, the arbor is turnedtoward the grind wheels 2 and 8 wherebythe electro-magnet is energized and the ring securely held, and the arbor is then moved so that the side of the ring contacts with the grind wheels. The grind wheel 8 moves at a slower speed than the grind wheel 2 and causes the ring and arbor arm to rotate. It will be apparent from Fig. 6 that the lines of contact between the piston ring and the grind wheels are substantially removed from the centers of rotation of the wheels. By this arrangement, the lineal speeds of the portions of the wheels contacting with the inner and outer portions of the rings are substantially equal and a more even grinding is thereby obtained. When the surface of a ring has been ground smooth,

the arbor and arm may be pulled away from the wheels and reversed so that another ring mounted on the other arm may be ground and the firstmentioned ring may be reversed in position for grinding the opposite side in the next operation.

I claim:

1. Piston ring grinding apparatus comprising a pair of wheels spaced apart, one of said wheels being made of abrasive material, an arm having a drum rotatably mounted thereon and upon which a piston ring may be placed and held during a grinding operation, electromagnetic means within the drum for contracting the ring upon the drum during rotation of the drum in a grinding operation in the shape the ring will assume in use, said drum and wheels being mounted relatively movably, whereby the ring on said drum may be passed between said wheels in the axial direction of, the drum.

2. Piston ring grinding apparatus comprising a pair of wheels laterally spaced apart, one of said wheels being made of abrasive material, an arm having electromagnetic means rotatably mounted thereon for holding a piston ring thereon while rotating during a grinding operation in the shape it will assume in use, said means being movable to and from the wheels in the direction of the axis of said means in such position that opposite sides of the ring contact with difierent wheels.

3. Piston rin'g grinding apparatus comprising a pair ofwheels spaced apart, one of said wheels being made of abrasive material, an arm having a drum rotatably mounted thereon for holding a plurality of piston rings thereon, electromagnetic means for holding the rings contracted on the drum while rotating in substantially the shape to be assumed in subsequent use, said arm being mounted movably in the direction of the axis of the drum between said wheels.

4. Piston ring grinding apparatus comprising a pair of wheels spaced apart, one of said wheels being made of abrasive material, said abrasive wheel having a substantially greater diameter than the other, an armhaving a drum rotatably mounted thereon for holding a plurality of p n ton rings, and electromagnetic means within the drum for holding the rings on the drum while rotating during a grinding operation in substantially the shape to be assumed in subsequent use, said arm being movably mounted to enable the drum to be moved between the grind wheels in the direction of the axis of the drum.

5. Piston ring grinding apparatus comprising a pair of wheels spaced apart, one of said wheels being composed of abrasive material, means for rotating each of said wheels, one oi. said wheels having a substantially greater peripheral speed than the other, a drum for holding a plurality of piston rings, said drum being mounted rotatably, electromagnetic means within the drum for holding the rings on the drum while rotating during a grinding operation in substantially the shape to be assumed in subsequent use, said drum being mounted for axial movement adjacent said wheels so that the drum and rings may be moved between said wheels.

6. Piston ring grinding apparatus comprising a pair of wheels spaced apart, one of said wheels 7 a,oes,osa

being made of abrasive material, an arm having a cylindrical drum rotatably mounted thereon for holding a plurality of piston rings to be ground, said drum having an electromagnetic winding therein, for holding the rings on the drum while rotating during the grinding in substantially the shape to be assumed in subsequent use, said drum and wheels being mounted movably with respect to each other in the direction of the axis of the drum whereby the rings on the drum may be passed between said wheels.

'7. Piston ring grinding apparatus comprising a pair of wheels spaced apart, one of said wheels being made of abrasive material, an arm having a cylindrical drum rotatably mounted thereon for holding a plurality of piston rings to be ground, said drum having an electromagnetic winding therein, and an outer sleeve of nonmagnetic material, said electromagnetic winding drawing the rings upon the outer sleeve into the shape the rings will assume in use, and means for maintaining said winding energized while said drum is rotating during a grinding operation.

8. Piston ring grinding apparatus comprising a pair of wheels spaced apart, one of said wheels being composed of abrasive material, a drum for holding piston rings slidably mounted adjacent the wheels, said drum comprising a non-rotatable spindle, an electrical contact ring on the spindle, a core piece rotatably mounted on the spindle, an electromagnetic winding on the core piece, and a sliding electrical contact between the spindle contact ring and said winding.

9. Piston ring grinding apparatus comprising a pair of wheels spaced apart, one of said wheels being a grind wheel and the other being a work rotating drive wheel, an arbor rotatably and slidably mounted adjacent the wheels, said arbor having a pair of rotatable drums for holding piston rings during grinding, each of I said drums having an electromagnet therein for drawing the rings into the shape to ,be assumed during use.

10. Piston ring grinding apparatus comprising a pair of wheels spaced apart, one of said wheels being composed of abrasive material, an arbor rotatably and slidably mounted adjacent the wheels, said arbor having a pair of spindle arms each having a drum rotatably mounted thereon for holding piston rings during grinding, each of said drums having an electromagnet therein for drawing the rings into the shape to be assumed during use, the arbor being mounted on a spindle having an electrical contact, the arbor having a pair of electrical contacts one for each electromagnet, the said arbor contacts being positioned to engage the spindle contact when its corresponding arm is substantially aligned with the space between the wheels.

11. Piston ring grinding apparatus comprising a pair oi wheels laterally spaced apart, one of said wheels being composed of abrasive material, a rotatable magnetic drum having a plurality of pins extending axially thereof for holding a piston ring during a grinding operation, said magnetic drum being slidable to and from the wheels in such position that opposite sides of the ring contact with different wheels.

CHARLES IRA LOTT. 

